We used to make Sprouts at home. I still remember the process of making sprouts and want to share the oldest technique that I know.
Green gram/Black chickpeas/ black-eyed cow beans you have to wash well the beans, if any stones you see remove it then soak in water for 8 hours(usually we will do this step in night). After 8 hours strain the water and put the bean in a clean dry cloth and place it a hanging position. The next day you can see sprouts on the side. If you want longer sprouts the number of days will increase and you have to sprinkle the water of the hanging bag.
Nowadays it is available in stores and made everything available to eat.