If your phone is good, it will only pair when you tell it to Some older Android, Windows Phones, possibly iOS (not 100% sure), and Blackberry had some exploits

If your phone is good, it will only pair when you tell it to Some older Android, Windows Phones, possibly iOS (not 100% sure), and Blackberry had some exploits around Bluetooth More-or-less any current phone (with current updates) should be safe from that. Key being: it needs to be kept up-to-date