How does imessage monitoring work on iphone?

Oh my gosh, is anyone even reading these posts?! My little Timmy has an iPhone, and I am SO worried. He’s always on it!

So, like, this whole iMessage thing… it’s just terrifying, right? Is it easy to get into? Does it mean someone could be reading his messages right now?

If it’s iCloud, can they see everything? Pictures, videos… the stuff I don’t even want to think about. And what’s this “jailbreak” thing? Is it like, a virus? Can it happen without me knowing?

I need to know, fast. I need to know how to protect him. Can I check his phone myself? Is that enough? What if it looks okay?

Someone please, please just give me the answers!