He's getting our call logs

So there's a guy who likes my best friend and he's kinda psyco type. He's behaving little sus and we think he's getting everyone's call logs in the group. He always texts my friend whenever we are talking about him in his absence. I don't know if that's a coincidence. He always asks one of the friends if xyz person is doing well and xyz person was last dialed from his phone. That's creepy. One day he was talking about how my best friend called her ex soo many times on a particular date. He keeps on doing these things and can manipulate and read people's mind very well. One friend of ours saw alot of website tabs were opened in his laptop. And he just know when we are talking about him and to whom we are talking for how long. My question is, is it really easy to hack phones and get call logs or recording or maybe whatsapp message and calls?