 The system does not have an active digitizer - no active stylus will work.  You can use a standard generic capacitive stylus but if you're looking for Surface-type features, you've purchased the wrong system - yours does not have the required hardware.  It cannot use a pen designed for a pressure-sensitive screen.    
Prior to my XPS 15 9510, I had an HP Spectre and a Microsoft Surface Book. I loved the Surface Pen and used it exclusively with my Spectre also. I tried using it on my Dell XPS, either it doesn't work, or the battery is dead. I don't want to buy a new battery to test it, if it's not compatible. I've looked online to see if it will work, and according the Microsoft the pen uses N-Trig technology, I'm not sure what that means, or if Dell supports it.  With all that said, does anyone know if the Surface Pen is compatible with the Dell XPS 9510 touchscreen with OLED display, and if not, what is a compatible pen? I've read conflicting statements as to what pens will and will not work with my particular Dell. I would appreciate any help or suggestions.   
What pen to use with new Dell XPS 15 9510 with OLED display?