Unity runs in background but loses keyboard input

I've been looking all over for this answer! Help oh great and powerful ones!!

I'm working on software to help live streaming.

Run In Background is check, so Unity runs in the background just fine, but loses all keyboard inputs.

I'm wanting to have focus on another program "Video Game" and send keyboard commands to Unity.

I'm an 3D artist, but I have some programming knowledge, if you could point me in the right detection or even better, type it out, I would be much appreciating!