How to model thread-like objects

it depends.
if its wool like ur pic you would have to do some fuckery with nurbs and somehow have awsome UV's

if its a surface of shirt it would be alot easier, substance painter have several of wool materials. just have the mesh unwrapped

>>534955
If it's up close and you can really see the weaving like that, you could do it with a procedural solution e.g. Houdini. Medium distance maybe displacement will look good enough (either procedural or image-based). From farther distance, normal/bump will be sufficient.

This reminds me of a tutorial i never got around to trying out. Maybe this could apply if you understood what the guy was doing.
https://www.youtube.com/watch?v=YLAzwEeml6c

>>534955
For Blender there's an addon that could probably do it, check this thread: https://blenderartists.org/forum/showthread.php?375378-tissue-by-Alessandro-Zomparelli&p=2899913&viewfull=1#post2899913

>>534955
If you're using it for a game or whatever, just fake it.
Use tesselation or even a parallax map would be enough.