Only one element from -> the_category

for a display of categorynames I use this expression

<?php the_category(‘
‘) ?>

inside my header.

It shows all categories and subcategories, like it should.

What I need if to show only the deepest element only. In the moment I am not able to breaack this expression into smaller pieces. I only need one categoryname.

If someone could help or give a tipp, thanks a lot.

Katasun