I would start by shutting off the circuit and searching to see if anything else goes offline (do not trust the labels to be accurate or exhaustive). As an example when we bought our house there was a circuit that was labeled only as garbage disposal, but it also had 1 kitchen counter outlet and the hood vent/microwave combo on the circuit.
Once you confirmed that there is nothing else on the circuit, or disconnected everything, see if it keep tripping.
If it does, it seems to me it is one of 3 things a bad breaker, a bad connect/path to ground, or a damaged wire. Whether at that point you feel you need to call an electrician depends on how willing you are to learn.
Checking the connections on an outlet is pretty easy (and if there is really only the garbage disposal) then you likely only have connections at the outlet and in the breaker box.
Anything in the breaker box may or may not involve working in a box with hot wires (unless you have a service disconnect outside of your breaker box, at least the wires to the line side of the main breaker will be live). The connections are no more difficult to check, but you might not feel comfortable with prospect of working around live wires.
Damaged wire could be anywhere, even buried in the walls. The wire could have rubbed through and is shorting, a mouse could have eaten the insulation, a nail/screw could have pierced the insulation ...
