Scroll down to the section labeled INTERACTION and tap on AssistiveTouch.
On the next screen, toggle AssistiveTouch to the green On position.
A white circle with a grey box will appear on screen. Tap this circle to expand it to a big box on screen. The square Home button at the bottom of the box functions exactly like the physical home button – you can use it to single tap, double tap, or long press the home button even if there is a hardware problem. The grey box remains visible and usable in all apps.