were watching, were keeping under surveillance, looked after, took care of
Том не заметил, что за ним следили.
Tom didn't notice that he was being followed.
Я почти уверен, что за нами следили.
I'm almost certain we were being followed.
Ранее вы следили за этим профессионально, не так ли?
You used to follow this professionally, didn’t you?
— Жизнь других (2006)
Билл не уверен, как его нашли — может быть, за ним следили.
Bill isn't sure how they found him—maybe he was being followed.
— Какой чудесный день (2012)
Ты уверена, что за тобой не следили?
Are you sure no one was following you?