Cracking or popping sounds in the feet can either be a benign symptom or they can be a symptom of having damaged certain structures in the feet or ankles.
Sometimes, the sound results from small bones in the foot moving through stiff tendons. This is entirely normal and is not something that you need to worry
about. This would be more like if the noises are long standing and if you haven't every had any major injuries likes sprains to the foot or ankle.
On the other hand, if the sounds are new, and if you recently had a bad sprain, or if you have been exercising more vigorously recently (for example lots of running), then the popping noises are more likely to be the result of the sprain or of an over use injury. In this case, you may want to try resting for a while from vigorous exercise to see if the symptoms subside.
If not you may want to see your primary care doctor
or your podiatrist
. You should see your doctor sooner if you are also having any type of pain or swelling in the feet. In the meantime, make sure to wear comfortable shoes with good support.