How to verify the pitch #of nuts?

I'm confused, true position has nothing to do with thread pitch? 

But to confirm the pitch of a threaded feature you can do it many ways, with varying degrees of accuracy. 
I would recommend a thread plug gage.
A pitch gage set (cheap and easy)
Make a mold of the part and check it with an optical system and measure it... 

Thank you.

For any given thread, the pitch and direction should be unique. If wrong number or direction was given in the program, the result could be shifted away from real TP...

Thank you.

For any given thread, the pitch and direction should be unique. If wrong number or direction was given in the program, the result could be shifted away from real TP...

You can also not rely on the measured diameter when applying a pitch to an auto-feature, unless you have done some addition work beforehand to ensure your probe is always contacting on the crest of the thread for each hit.  Even then, you would only be measuring the minor diameter.

Neil Challinor  Based on those conditions, should I use sleeve to help measure nut TP for accurate result?

Applying a pitch to the auto-feature should give reliable measurements for position, it's just the size that you cannot really rely on.

Got it. Thank you

I suppose measuring threads with the wrong pitch would create an axial error for the location, which would effect the TP results 

I have, rarely, found exceptions to this.  Depending on how threads were cut, it's possible for the minor/pitch diameters to not be concentric.