Apple Cash
I continually get a message I have insufficient funds from Apple Cash even though I am not trying to purchase anything. I don’t even use Apple Cash. Is someone trying to purchase something through my account?
iPhone SE, iOS 10
In order to use Apple cash by someone else they would need to be sharing your Apple ID. You can see who is sharing it by going to Settings and tapping on your name at the top. Any devices using your Apple ID will be listed at the bottom.