\documentclass[a4paper,11pt]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{verbatim}
\usepackage[linkcolor=blue,colorlinks=true]{hyperref}

\title{Title}
\author{}
\date{}
\begin{document}
\part{Part1}
\label{s:1}
\chapter{Chap1}
\label{s:2}
Text.

\chapter{Chap2}
\label{s:3}
Text.

\section{Section1}
\label{s:4}
Text.

\section{Section2}
\label{s:5}
Text.

\subsection{Subsection1}
\label{s:6}
Text.

\part{Part2}
\label{s:7}
\chapter{Chap3}
\label{s:8}
Text.
\hyperref[s:5]{Section2}
\hyperref[s:2]{Chap1}
\hyperref[s:7]{Part2}


\end{document}
