- Backup of your iPhone using iTunes.
- Use the "Backup" button to backup your device. You will need to check the "Encrypt iPhone backup" option if you are using iOS 12.
- Download Pinfinder
- Extract and run the program, and wait for a few minutes you should see your restrictions passcode printing on screen

Pinfinder can recover restrictions passcodes from encrypted backups with iTunes.
NOTE: Pinfinder cannot recover unlock PIN which is used to get into your device; it will only recover the restrictions passcode