[TYPO3-mvc] Can I get a list of categories that have items? TYPO3 sys_category table?

[Dmitry]

Hi all,
Im use TYPO3 7.6.2 In my extension I'm use sys_category. 
In controller, I get some objects finding by category. It's work fine.

$objects = $this->objectRepository->findByCategory($categories);
$this->view->assign('objects', $objects); 

Object 1 - Cat 1, Cat 2

Object 2 - Cat 3, Cat 4

Object 3 -Cat 1, Cat 4

Can I get a list of categories that have these objects? Like Cat1, Cat2, Cat3, Cat4 (I have a lot of categories.)