That is the Cam Position Sensor(CPS), black cover with 2 screws, and it sits on the syncronizer, you should change both if there is a noise.
Recommended replacement time is 100k miles.
But you can remove the CPS and see if it has disintegrated inside, not uncommon issue, if so just replace that and see if noise is gone.
Syncronizer going out will cause a squealing noise vs clicking noise, as bearing/bushing is failing.
Good diagram in the #4 post here: 1998 explorer 4.0 ohv cam sensor alignment - Ford Explorer and Ranger Forums "Serious Explorations"®
In diagram CPS is called CMP
The syncronizer is similar to a distributor setup, it is driven by the cam shaft gear and it also drives the oil pump, so if syncronizer fails you lose oil pressure instantly, not a good thing at highway speeds.
CPS sits on top of syncronizer.
Replacing syncronizer does require you to match the crank and cam timing, so read up on it BEFORE starting, replacing just the CPS is easier.