My whirlpool dishwasher is making a high squeaking sound when washing, what can the problem be?

SOURCE: Dishwasher Making Loud High Pitched Noise.

How deep do you want to get into this?It sounds like the wash pump motor bearings that are worn.You can pull the unit out flip it over and wd40 the bearings in the motor or you can replace the bearings.Try to lube them first.

SOURCE: LG DISHWASHER LD-1204W1

Try turning your tap off a bit till the noise stops but the dishwasher still fills, it can just be due to a bit too much pressure on your water valve.
hpe this helps

SOURCE: Dishwasher Making Loud High Pitched Noise.

A loud high pitch whine while running the dishwasher means that there is something caught in the chopper assembly. To get to the chopper assembly you need to take the racks out and take the pump apart from the inside of the dishwasher. The chopper assembly looks like a metal grate with holes in it. And it might not even be stuck in the grate but somewhere in the pump area due to the water being pumped out, so the best idea is to take the whole thing apart and clean everywhere. However I do not recommend doing this unless you are completely certain you will remember where the screws and gaskets go, otherwise you risk damaging your pump or house from a leak or improper installation. You have been warned.

SOURCE: We have a Whirlpool undercounter

drain is probably clogged with something need to get the water out and see if you can remove it

SOURCE: The Whirlpool dishwasher DUB770XB makes a grinding

The pump probably has broken off a fin and it's rattling around in the impeller. also check to see if there are any foreign objects in the bottom, such as broken glass seeds etc.