I don't think you will be able to get it out. There was(is a youtube) video out on adjusting the sensitivity of the Spen. Maybe you could check that out. It shows the pen with the button removed. I looked at the video in 2014 but cannot recall whether tge "nib" was visible. You may have to buy a new spen.There's no nib part in the slot. The nib broke outside.
Is there any way to completely open or disassemble the spen, without breaking it?
I was able to get the remainder out with a sewing pin, it came out quite easliy.