Set up the depth of the subsection enumeration also in the Table of Contents

Question

In order to set the level until which (sub)sections are numbered, a user can set up the counter secnumdepth.

\setcounter{secnumdepth}{whatever}

The trick works completely fine. However, if you try to increase the depth of the enumeration (for example up to 4), the change is not reflected in the Table of Contents at the beginning of the document. Specifically, it continues to show just the old depth of Chapter-Section-Subsection. No subsubsections appear How to add the numeration automatically in the Table of Contents?