Can a uhaul truck be used to obtain a cdl?

No. U-Haul trucks are under 26,000 lbs. GVWR... the only way you would need any type of CDL to operate a U-Haul truck is if it were hauling a sufficient quantity of hazardous material that it was required to display placards, which is more than likely going to be a practice prohibited by U-Haul.

The best way (and, really, only feasible way) to obtain your CDL is to attend a truck driving school. Most community colleges have them, and many transportation companies host their own driving schools, as well.