\documentclass[a4paper]{report}
\usepackage{xcolor,soul}
\definecolor{lightblue}{rgb}{.60,.95,1}
\sethlcolor{lightblue}


\begin{document}
\tableofcontents
\chapter{ich}
bla
\chapter{\hl{er}}
\section{ich wieder}
blubb
\section{\hl{dann nochmal er}}
\end{document} 
