How do I disable the clicking sound when I put my iPhone to sleep?

Apple added Haptic feedback to the Sleep/Wake button and Ring/Silent switch in iOS 10. This has replaced the vibration sound and sound your iPhone made when you put it to sleep using the Sleep/Wake button. There doesn’t seem to be a way to bring back the old sounds, but you can disable the new Lock Sounds in the Settings app. Just navigate to Settings > Sounds and scroll down to the bottom of the page, then tap the Lock Sounds slider so it is OFF/WHITE. This will disable the Haptic feedback vibration your phone makes when you put it to sleep/lock it using the Sleep/Wake button.