I have had success acquiring Demodex by waiting until night in the dark, when they are most likely to leave the follicles and be on the surface of the face. They can be collected by scrapping the face with a microscope slide, then examining the slide microscopically for movement. It might be difficult to collect enough specimens for analysis in this manner and some skin types are probably better than others for harvesting the mites.

You can pull out the eyelashes or hair on the eyebrows and look at them under a microscope. you will see the demodex on hair roots

Thanku Yulia and Jonathan for replying