Question

how can we demonstrate the formation of magnetic field surroundings a magnet

Answer 1

put many small pieces of iron or steel and put it around the magnets you will see a pattern look like a loop which is a magnetic field around the bar magnets

Answer 2

You can demonstrate it by a simple activity
Place a bar magnet on a table then put a cardboard on the magnet place small iron nails then you can observe magnetic field of magnet