Hi
I have noticed a white substance formed under my penis foreskin. My penis is itching and producing some smell due to it. Please advice what to do.

Sounds like thrush/yeast. Time to see your doctor.

By the way, I have moved your post from Heating & Air Conditioning to Men's Health. Please try to choose the proper forum for your questions.

Yes, infection, time to see the doctor

Yes, accumulation of 'smagma' under foreskin accumulates when you don't pull your foreskin back to clean, causing infection. Left untreated, destroys the skin.