Answer:
Step-by-step explanation:
If your mobile device is an iphone, then there is no debug mode except jailbreak.
If it is Android, then it depends on its version. All you have to do for some is to connect USB to a computer, a menu will show on your phone and ask if you want to allow USB debug mode. Other versions you need to enable USB debug in System Settings.
If everything else fails, then follow the other helper's advice.