I have a USB pen style micro scope and the problem with this type of product is that in order to get a high enough magnification to start looking for any wear the working distance is only 3mm which because of the size of the end of the unit you cannot get in the correct place to see the wear points without hitting the body of the cartridge.
The other issue is holding it steady enough and doing small adjustments without everything disappearing off the screen and many of holders are good enough and either slip or jump. Yes you can get pictures but it does try the patience somewhat. At lower magnifications they are good for alignment and general views.
Be careful on the magnification (mine proudly states 200x) as but most of this is because your screen is 200 times bigger than the sensor and some of the resultions are "interpolated" where a 640 x 480 pixels is increased to high resolution by guess work which makes it look like a water colour painting of a stylus.
Because of the low cost I have ordered the one suggested by Alec and also the same companies 60-120x version as they appear to have a greater working distance.
However the small depth of field (only a very small area in focus) at higher magnifications means most of these are designed more for flat objects/slides rather than complex 3D shapes like styli.
I have a low cost "macro rail" to play with as well so I will try them out and feed back to the forum
I suspect that you are going to need "proper" macro equipment and possibly focus stacking (combining a number of photographs where the focus point is moved minutely between each one) to get really good shots.
There are some shots I tried with my USB in this thread viewtopic.php?f=19&t=86429&p=716515&hilit=Stylus#p716515
(LP) Rega Planar 3/RB300/A&R-P78+FG2 (CD)Rega Planet-2000, (Amp) Musical Fidelity A3.2, (Speakers) Rega RS3