EMB-175 Captain reported returning to departure airport after experiencing pitch trim anomalies during climb.

Narrative

During flight ZZZ-ZZZ1 shortly after take off I was flying the aircraft and trying to adjust the pitch trim and the pitch trim would not adjust from the takeoff pitch trim setting. we attempted to adjust the trim from all locations but the trim was not adjusting. We turned on the auto pilot and discussed our next actions. I asked ATC to level us off at an Altitude so we could begin trouble shooting the issue. While the Autopilot was engaged we got an AP (Autopilot) PITCH MISTRIM caution message. We ran the QRH for that EICAS message but obviously were not able to trim the pitch. we discussed this shortly and decided to re-engage the AP to reduce workload while we further troubleshooted the issue. I [requested priority handling] with ATC and told them we would be returning to ZZZ. I asked for vectors while we troubleshooted the problem further and ran necessary checklists. After discussing the issue we concluded since we could not adjust the trim from any location that the pitch trim was either jammed or unresponsive and that in essence it had failed. so we agreed the proper QRH to run was the PITCH TRIM FAIL QRH. We completed that QRH and the pitch trim did not return to normal. We completed the rest of the QRH; I flew the aircraft and the FO set up the aircraft for the return to field. we performed our procedures returned and landed without incident.