In addition to what @userella mentioned, it's just as easy to go to your BT settings and see if a device is paired to your phone that you did not pair. Delete anything you do not recognize and block it from reconnecting in BT advanced settings. You can turn BT off when you are not actively using it (this could be problematic if you have paired watch). If you open your BT settings or pull down the quick panel when you suspect someone is on, you will see what's currently connected. Curious as to why you think someone Bluejacked you.
