SO this is a nice app that I use! It is a great software to make graphics and sketches as the name suggests. It's a freeware and it has some great functionalities to offer in the pro version.
Checkout all the features and more it offers:
https://www.sketchbook.com/?locale=en

I use it on my Android device and really like using it
If you have a touchscreen device I highly encourage you to check it out!

thanks for sharing !