On the phone, select Settings -> About Phone. Locate the option called Build number and press on it 7 times in succession. You will then find that Developer Options is enabled in the About Phone menu.
Tag: developer
How to put phone into USB Debugging mode from Developer Options
First enable Developer Options. On the phone, select Settings -> About Phones -> Developer Options. Locate an option named Android debugging and change the toggle to On. The phone will now be in USB Debugging mode.