Possible causes of clicking sound in head ...
Are they accompanied by headaches (sharp or dull ones)? You need to look into Temporomandibular Joint Headaches. TMJ is really a muscle-contraction type of pain, sometimes accompanied by a "clicking" sound in the head, it's caused by mal aligned teeth. You need to mention these symptoms to your dentist/orthodontist.
Typical treatment includes: relax of muscle area being affected, training in biofeedback, using a bite plate and in severe cases sometimes surgical correction of malocclusion.
Also, remember that bone carries sound. If you're walking when you are having this problem, you might seek some kind of orthopedic consultation for your neck or back, especially if you have had any kind of trama or injury in the past.
If the clicking seems unrealted to a headache or movement, ask your doctor about tinnitus.
If the clicking sound comes with blinking, you should see your optometrist. Air can become trapped between the eye itself and the upper or lower lids, so when you move the eyelid you force the trapped air pocket out and you can hear a sound. If you notice this after having a blow to the eye area, it can indicate an orbital fracture which can be serious. Air from your sinuses can infiltrate into the tissues around the eye and lead to infection.
Always see your doctor when you have concerns, but remember some doctors don't understand your symptoms. You may see an general practicioner when you need to be at the Dentist, Optometrist or ONT. I know that's not much help but it's true. There are too many specifics and specialists exist for a reason.
No matter what, make your chances of accurate diagnosis better by being clear and concise with your MD. Be careful to describe symptoms fully, and don't forget to note any trauma or illness that you may have suffered preceding the development of the symptom - like a blow or infection.
Good luck.