If it is ensured "by hand" that each index-entry occurs only once per page within an \index-command, then as a starting-point I can offer a macro \Autodestinationindex which takes an optional argument and a mandatory argument.
The mandatory argument is the phrase for the index-entry.
The optional argument can hold a key-value list with the keys Up=... and Left=....
It is just a starting-point because if I get the way in which makeindex works right, it does not take into account the case of an index-entry not specifying a list of pages like 1, 7, 15 but specifying a range of pages like 7-9. (If you need a more sophisticated mechanism you are probably better off not attempting to accomplish it on TeX-macro-level but by means of an index-style-file tailored to your needs.)
\Autodestinationindex internally uses the counter-macro \countallindexentries for creating a named destination which in relation to the reference-point of the leftmost item of the phrase for the index-entry in the text is shifted upwards by Up=... and is shifted to the left by Left=....
\Autodestinationindex also creates an index-entry for the phrase for the index-entry where the page-number forms a hyperlink to the destination.
If the optional argument is not specified, hyperref's defaults for \Hy@raisedlink are used.
Compile with an engine based on pdfTeX, then run makeindex on the resulting .idx-file, then compile again.
View the resulting pdf-file with a large zoom-factor to see both the horizontal and the vertical scrolling-behavior depending on Up=... and Left=... after clicking the link in an index-entry.
The \fboxes/framed boxes can be omitted as they are only for easing up visualizing the scrolling behavior: The bottom left corner of the \fbox is close to the reference-point of the leftmost item of the textual phrase, thus you can more easily judge where the named destination/target is placed in relation to that reference-point.
The phrase forming the index-entry should not start with a break-point as otherwise a break might occur between the (invisible) point in the pdf-file forming the named destination which the pdf-viewer will scroll to the top-left-corner of the window where the pdf-file is displayed and the leftmost item of the phrase that shall be seen in the top-left corner of the window where the pdf-file is displayed when clicking the hyperlink.
\documentclass{article}
%\usepackage[hyperindex=false]{hyperref}
\usepackage{hyperref}
\usepackage{makeidx}
\makeatletter
\newcommand*\countallindexentries{1}
\newcommand\globalstepcountallindexentries{%
\xdef\countallindexentries{\number\numexpr\countallindexentries+1\relax}%
}%
\NewDocumentCommand\CreateAutodestinationindexentry{mmm}{%
% #1 name of destination/target
% #2 phrase forming the index-entry
% #3 key-val-list for shifting the destination/target up/left
\RaisedHypertarget{#1}{#3}#2\index{#2|hyperlinkwithhyperpageneutralized{#1}}%
}%
\newcommand\hyperlinkwithhyperpageneutralized[2]{%
{\let\HyOrg@hyperpage=\@firstofone\hyperlink{#1}{#2}}%
}%
\ExplSyntaxOn
% key=value-interface by means of package l3keys:
%-------------------------------------------------------
% Macros holding default-values of keys
% \cs_new:Nn here instead of Up.initialize etc
% within \keys_define:nn in order to get an error-message
% in case of overriding/redefining an already existing
% control sequence.
\cs_new:Nn \__COUNTALLINDEXENTRIES_MOVEDESTINATIONUP: {\q_no_value}
\cs_new:Nn \__COUNTALLINDEXENTRIES_MOVEDESTINATIONLEFT: {\q_no_value}
\keys_define:nn { COUNTALLINDEXENTRIES } {
Up.cs_set:Np = \__COUNTALLINDEXENTRIES_MOVEDESTINATIONUP: {},
Up.default:n = \q_no_value,
Left.cs_set:Np = \__COUNTALLINDEXENTRIES_MOVEDESTINATIONLEFT: {},
Left.default:n = \q_no_value,
}
\cs_new:Npn \RaisedHypertarget #1#2 {%
% #1 name of destination/target
% #2 keyval-list
\group_begin:
\keys_set:nn{ COUNTALLINDEXENTRIES }{#2}
\exp_args:No
\quark_if_no_value:nTF{\__COUNTALLINDEXENTRIES_MOVEDESTINATIONUP:}
{}
{
\exp_args:NNo
\cs_set:Npn \HyperRaiseLinkDefault{\__COUNTALLINDEXENTRIES_MOVEDESTINATIONUP:}
}
\exp_args:No
\quark_if_no_value:nTF{\__COUNTALLINDEXENTRIES_MOVEDESTINATIONLEFT:}
{\Hy@raisedlink{\hypertarget{#1}{}}}
{
\Hy@raisedlink{
\kern\dimexpr-\__COUNTALLINDEXENTRIES_MOVEDESTINATIONLEFT:\relax
\hypertarget{#1}{}
\kern\dimexpr\__COUNTALLINDEXENTRIES_MOVEDESTINATIONLEFT: \relax
}
}
\group_end:
}
\NewDocumentCommand\Autodestinationindex{O{}m}{
% #1 optional key-val-list for shifting the destination/target up/left
% #2 phrase forming the index-entry
\token_if_macro:NTF \hypertarget
{
\legacy_if:nTF {Hy@hyperindex}
{
\exp_args:Nx
\CreateAutodestinationindexentry{IndexEntry\countallindexentries}{#2}{#1}
\globalstepcountallindexentries
}
}
{ \use:n }
{
#2\index{#2}
}
}
\ExplSyntaxOff
\makeatother
\makeindex
\begin{document}
Some text Some text Some text
\vspace{2cm}
In probability theory and statistics, the
\fbox{\Autodestinationindex{Laplace distribution}} is a continuous
probability distribution named after Pierre-Simon Laplace.
\vspace{2cm}
In
\fbox{%
\Autodestinationindex[Up=\dimexpr\baselineskip+\fboxrule+\fboxsep\relax,
Left=\dimexpr\fboxrule+\fboxsep\relax]{probability theory}%
} and statistics, the Laplace distribution
is a continuous probability distribution named after
Pierre-Simon Laplace.
\vspace{2cm}
In probability theory and statistics, the Laplace distribution
is a continuous probability distribution named after
\fbox{\Autodestinationindex[Up=2cm, Left=1cm]{Pierre-Simon Laplace}}.
\printindex
\end{document}
