How to use \polishhook symbol

I think you are looking for the standard LaTeX accent \k

\documentclass{article}
\usepackage[T1]{fontenc}


\begin{document}

\k{E}

\end{document}

With \k{E} under T2A encoding you get a composite character, which might be sufficient for your purposes. However, the composition is quite bad for \k{e} and not optimal for \k{A} and \k{a}, as can be seen from the picture

If you need both Russian and Polish text in your document, you should use babel features, so that the correct font encoding will be automatically chosen based on the current language.

\documentclass{article}
\usepackage[T1,T2A]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[polish,russian]{babel}

\begin{document}
Михаил Сергеевич Горбачёв

\foreignlanguage{polish}{Lech Wałęsa}

\end{document}