Anti-Theft Alarm for headphone status is a way to keep yourself aware of your phone's presence.
1- Select Anti-Theft from the home screen.
2- Anti-Theft screen opens up.
3- Tap "Headphone" from the options to open up an alert dialogue. If you are activating any Anti-Theft alarm for the first time then you will be asked to set up a PIN in the first place. The creation of a PIN is two steps process, first, create a PIN and then re-enter the PIN to confirm.
5- Once the PIN created, Go back to the anti-theft screen. Plugin the power cable and tap on "Headphone". The alarm will not activate if headphones are not plugged into your iPhone. Make sure the headphone cable is connected.
6- Next, tap "Activate" on alert. The PIN screen will be displayed. An alarm will buzz off when the phone detects that the headphone cable has been removed from the jacket. The buzzer can be deactivated by putting in the PIN code you created in step 4.