If you wanna see the deformation on the UV right click on your model >> Current State to Object. This will create a new object and UV that has all the stretch and deformations that you did using sculpting; the problem with this is that depending on your model you may end up with an object with thousands of polygons.
if, on the other hand you Bake your object, you will be using Normals and Displacement to create the illusion of a high Poly mesh using a low poly object, so this does not affect your object polygon nor its UV.
My recommendations for Sculptind are:
-Work with your UV’s Before start Sculpting, UV Wizard it is not always a good choice for Good UV’s, specially with complex models, you may need to do it manually.
-Create Low Res Base Mesh with a UV already edited and you will not need to turn On Optimal Mapping.
-Bake your Sculpt Object using 32 bits and using 2K Resolution or Higher (all depends on your model).
I hope this helps you.
Good Luck
Imagination is the best tool…