Do the following on your phone:
Go to settings.
Now in settings, scroll all the way down and go to About>Software device.
Now in Software locate "build number" of your device. Tap the build number for 7 times to enable developer options.
Once you’ve enabled developer options, back out two menus and developer options will appear in settings just below the About phone option.
Open developer options and there should be an option “USB Debugging”. Turn on the small icon next to it and that’s all.