Well, the thing with mobility drills is that you really need a video or at least a picture to understand properly. Mobility is about precision and details and a mere description isn't really enough.
I personally never had any issue with ankle or wrist mobility and never had to work on these. But the best way to improve ankle mobility is EQI exercises (Eccentrics Quasi-Isometrics which are talked about in one of my books).
Use a seated calf machine, put some weight on (but not too much). Set-up as if you were going to do seated calf raises and go to the lowest position you can reach and hold that position as long as is tolerable... as the muscles fatigue there will be less and less tension and the muscle will stretch more and more. Shoot for a total of 3 minutes. The ultimate goal is to be able to do the whole 3 minutes in one shot. But that might take you a while and is not necessary to improve mobility.