Add in the ham bone, onions, thyme, celery, carrots, and split peas to your Instant Pot.
Add the water or stock and then put the lid on the Instant Pot. Seal the valve and make sure that the Instant Pot is not over half-way full.
Put the Instant Pot on "Manual" setting using high pressure. Set the timer for 20 minutes.
Once the timer is up, allow the pressure to naturally release. This could take around 15 minutes.
Once it has finished, open the lid and season with any other ingredients you desire. You can now serve your split pea soup with ham.