It would appear that with the right to left swipe of your finger, after launching the DJI GO4 App, you can select the new home point as being You/Your Controller.
Great for when you are moving in a vehicle or boat.
well... duh, it's a well documented feature. It also sets it the HP to your current position at that point in time so if you keep moving, don't expect the drone to come to where you've moved to.