Something like this?
\documentclass{article}
\usepackage{steinmetz}
\newcommand\polar[2]{#1 ^{\,\raisebox{3pt}{\scriptsize$\phase{#2^{\circ}}$}}}
\begin{document}
$z = \polar{1.19}{-78.2039}$
\end{document}

Works fine in align
:
\documentclass{article}
\usepackage{steinmetz,amsmath}
\newcommand\polar[2]{#1 ^{\,\raisebox{3pt}{\scriptsize$\phase{#2^{\circ}}$}}}
\begin{document}
\begin{align}
z_1 &= \polar{1.19}{-78.2039}\\
z_2 &= \polar{2}{33}\\
\vdots&\\
z_{10} &= \polar{4.1}{\sqrt{3}/6}\\
\end{align}
\end{document}

...and as a tikz
node:
\documentclass[a4paper,10pt]{scrartcl}
\usepackage{tikz}
\usepackage{steinmetz}
\newcommand\polar[2]{#1 ^{\,\raisebox{3pt}{\scriptsize$\phase{#2^{\circ}}$}}}
\newcommand*\rectangled[1]{\tikz[baseline=(char.base)]{
\node[shape=rectangle,draw,inner sep=2pt, rounded corners=4pt, thick] (char) {#1};}}
\begin{document}
A rectangled number \rectangled{$\polar{1.19}{-78.2039}$}: No problem normally as it is used as normal charakter and TeX can set it in the right position.
\begin{sloppypar}
A button with a longer name is marked using the same command and \rectangled{$\polar{2}{33}$} if it is set to the end of a line.
\end{sloppypar}
\end{document}
