Note: This is sweetened condensed milk such as Eagle Brand, not evaporated milk.
Using a heat proof bowl that will fit into your Instant Pot, pour the entire contents of one can of sweetened condensed milk.
Cover the top of the bowl with a piece of aluminum foil.
Get another piece of foil, and set the heat proof bowl on top of it. Bring the foil up over the edges of the bowl.
If you think it necessary, to keep the water from seeping in, you can add another piece of foil over the top of the bowl
Place a wire rack onto the bottom of the Instant Pot. Place the foil wrapped bowl of sweetened condensed milk on the rack.
Pour as much water as needed into the pressure cooker pot to come up half way on the heat proof bowl you placed into the Instant Pot.
Secure the lid on top of the Instant Pot. Set the valve to sealing.
Set the timer for 35 minutes. You can set the timer up to 45 minutes for a darker color, thicker sauce.
When the Instant Pot caramel sauce is done, use the quick release to release the pressure.
Carefully remove the bowl from the pot and whisk to blend.
Notes
The cook time varies greatly depending on the size/wattage of the electric pressure cooker as well as the size of the bowl used. A four cup batter bowl in an 8 quart Instant Pot electric pressure cooker was used for the photos show. The caramel took 45 minutes.