Creepy Friend stalking Comments

As the title says, I have a creepy friend who is someone able to find all of my comment history and randomly sends me the videos or comments on my comments. It wouldn’t be a problem besides the fact that they are doing it on literally every comment and post and it’s getting odd - can anyone do this? Do they need to be in your followers to do so? Would love some insight, I’m starting to get very creeped out…