How to check if someone can access y iPhone?

someone is able to turn airplane mode on and turn my cellular account off. i thought if you phone has all its ways to connect off then you can’t access your iphone. i left my network on and airplane mode off?

I was under the thinking that a iphone is not possible to be hacked etc… like everything i hear is that it’s not possible to hack a iphone. but someone is able to do whatever they want to my iphone like: change cellular toggle off or on, turn airplane mode on when it was off. there is also other setting that where charged also.

too many to mention please help. and yes it’s updated to the latest update a no i dont share or lend my phone to anyone.

[Edited by Moderator]