With the D750, you can use the older screw-drive AF lenses, such as the 60, 105 and 200mm AF-D Micros. I have both the 60 and 105, and both are superb. The 105, I've used as a portrait lens, and it's fantastic. The newer AF-G 105 has VR, but I'm not sure how useful that is, as it's pointless on a tripod, and of limited effectiveness anyway, at close distances. The older version is a lot cheaper s/h.
The older AI/S manual focus versions only focus to 1:2, or half life size, afaik. The AF versions, to 1:1 full lifesize. So a 1cm long subject is 1cm long on the film/image sensor. To achieve this, on the older MF lenses, and higher magnification ratios on all, you'd need extension tubes and/or bellows units, that kind of thing. Fiddly.