Hello,
This black spots under the skin of penis can be due to Fordyce spot. They are small, painless, raised, pale or white spots or bumps 1 to 3 mm in diameter that may appear on the shaft of the penis. The spots are a form of ectopic sebaceous gland, and are not known to be associated with any disease or illness and are of cosmetic concern only. They are non-infectious and a natural occurrence on the body.
I hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.
A blood vessel seen,not a problem.It would look black if it is a vein.