I’m making a 2D game that involve falling objects (bricks and bombs). The game is about catching falling eggs, but the player needs to watch out for bombs and brick. What should I do? 
PS The objects need to fall at random
Well, I assume that noone will code your game for you. Start here Unity - Manual: Scripting and here Learn game development w/ Unity | Courses & tutorials in game design, VR, AR, & Real-time 3D | Unity Learn.
For the random order use Random.Range(1, numberofobjects);
That sounds pretty straightforward. I whipped up a quick example:
It’s pretty self explanatory, but you can follow along what I did to get a sense of how to do it yourself.