\documentclass[a4paper, oneside, 10pt]{article}
\usepackage[utf8x]{inputenc}
\usepackage[czech]{babel}
\usepackage[unicode]{hyperref}
\begin{document}

\section{\texorpdfstring{Nadpis 1}{Nadpis 1}}
\label{sec:nadpis_1}
\subsection{\texorpdfstring{Nadpis 2}{Nadpis 2}}
\label{sec:nadpis_2}
\subsubsection{\texorpdfstring{Nadpis 3}{Nadpis 3}}
\label{sec:nadpis_3}
\paragraph{\texorpdfstring{Nadpis 4}{Nadpis 4}}
\label{sec:nadpis_4}
\subparagraph{\texorpdfstring{Nadpis 5}{Nadpis 5}}
\label{sec:nadpis_5}

\end{document}