B737 MAX 8 Captain reported during takeoff both pilots heard a loud squeal in their headsets that continued throughout the flight. Post flight; Maintenance found part of a jack pin of a pushback crew headset had broken off in the aircraft panel causing a short in the intercom.

Narrative

Flew prior leg with no issues. During takeoff (at rotation) both Pilots experienced a deafening loud squeal in our headsets. I had to yell at the First Officer (FO) that I was essentially NORDO; with no intercom or ability to hear ATC. This was not like a stuck MIC; just a continuous very loud screech. It remained regardless of Audio Signal Processor (ASP) selection. The FO indicated that he was still (barely) able to hear and transmit to ATC. We used the procedure to troubleshoot and after several minutes; found that it was an issue with the intercom and not the VHF radios. Even when intercom was deselected; there was a screech; but it was tolerable enough to still hear ATC. We ACARS's Dispatch just in case we had any additional issues. The screech became somewhat intermittent but remained for the majority of the flight. No ATC deviations occurred. Upon landing at ZZZ; Maintenance was called to investigate the cause. They found that during pushback headset disconnect; part of the jack pin had broken off and caused a short in the intercom. The Maintenance Tech said this is starting to happen frequently; and especially in MAX aircraft as they are taller than the NG's and are pulled at a downward angle during disconnect that can break off part of the pin and remain inside the aircraft panel and thus cause a short.