A DriveDX report may provide me clues to the health of the hard drive which is one of the most likely parts to be making a clicking noise, although this is less likely if the issue has been around for a year. The next most likely part is a fan. A third possibility is the speaker is making the clicking noise.
How often does the clicking occur? When it does occur how long does it last? Does it seem to coincide with anything specific you are doing?
Can you record any audio of it to include here?
Does the clicking seem to come from the left side, right side, or from the center?
Have you tried muting the audio when it happens?