The USPTO has published a patent application from Microsoft that adds some further sophistication to their 3D touch system.
The application, from the 3rd January 2014, was published on the 9th July 2015, and would add the ability to detect the angle of your finger above the screen in 3D space, and not just the position of the tip of your finger.
It would do this by not just detecting the tip of your finger or stylus, but also a position a but further back, allowing it to calculate the angle between the two.
Microsoft notes that this would allow users to point at a spot on a screen not immediately under your finger, and for the phone to know which part of the screen is being covered by your hand and actually move elements out of the way.
This would also for example allow the operating system to increase the size of elements such as keys on a keyboard as you approach them at an angle, needed for when you want to see what are are going to be touching.
The 3D Touch system would work with a wide variety of sensors, and it is likely the Intel Realsense system which is part of Microsoft Hello and which will be built into the Lumia 940 and 940 XL will also support such features.
The full patent application can be seen at the USPTO here.
Thanks Adrian for the tip.