Yes you can, very easily too. Each dispenser will come with a rubber gasket inside. The rubber gaskets job is to ensure a tight seat between the head of the dispenser and the canister. Some people want to replace this with a silicone gasket. Why? Silicone gaskets are neccesary if you intend to go beyond making whipped cream with your dispenser, and want to add hot liquids inside. Silicone can handle the heat while rubber cannot.
If you want to go beyond whipped cream with your dispenser, you can easily replace your rubber gasket with a silicone one. Just pull the rubber gasket out and replace it with a silicone gasket, it’s really that easy. You can purchase a silicone gasket here