Search for "microscope camera adapter" on your favorite shopping sites. The cheaper adapters have no optics. Without optics, images will have heavy vignetting.

Many of the microscope-camera adapters have T2 screw mounts on the camera side, including the AmScope model. The same adapter should fit either eye-piece or camera port. Use a T2-NEX adapter, instead of T2-Nikon or T2-EF, to fit it your camera.

[![adapter stack][2]][3]

See also:

* YouTube: [Attaching your DSLR Adapter to your Microscope][1] (AmScope)
* https://photo.stackexchange.com/q/62000/75526

  [1]: https://youtu.be/pzpHh1PQAEM
  [2]: https://i.sstatic.net/SWb6Tm.jpg
  [3]: https://i.sstatic.net/SWb6T.jpg