iPhone Bluetooth Hacked

My Bluetooth was hacked on my iPhone, the intruder lives right above me. Zero love for each other. After she was in my phone she got login for my airport and pretty much everything on my computer. Days were spent updating PW’s on routers, apps, computer logins, etc.

She’s back at it, so I keep BT off. Not much fun for the Apple Watch.

I notice that every time I open my BT it shows discovery mode. How can I change that? Also, I would like to add a security code to my BT.

Thanks