Hey Hritik! The first thing is probably to get some sort of stylus or digital pen. I'm aware of three options: 1) iPad + Apple Pencil; 2) Android tablet + stylus; 3) a Wacom tablet + computer.

I use 1). I have no experience with 2) or 3).

Once you have that you just need a drawing app for your device and practice. I use Procreate, but there are countless other apps.