Hello,
It is possible to open the pen, by removing the top cap with a knife or flat screwdriver and pressing SLOWLY from the usb port. Some pens are harder glued than others. Then you can press out the PCB. The PCB board is about 8,5 x 1,5 cm including the usb connector (or 6,8 cm without the usb connector) and 1,3cm thick at the thickest part and 0,4cm at the thinnest parts. The camera is not soldered to the pcb, it has a about 1cm long flex cable. The PCB without the housing weighs about 10 grams.
The camera part itself is about 9cm long and 1,7cm thick (with the housing).
But rememer that the frame per second rate is quite low, maybe around 10 or 15, so in fast movement the image will become blurry, so a camera with better f p s could be a better solution.