What do you mean when you say simulating circuits? If it's just beginner level stuff you can try out TinkerCAD, it has a built in Arduino programmer as well!! I'm using it to practice the circuits present in the book Make: Electronics.
If what you're looking after is advanced stuff then I've seen people mention LTSpice in the forums but then I have zero experience with it.
I've seen your other posts and it looks like you're a beginner just like me, I'd suggest watching YouTube videos on how to use these tools, they're a lot more intuitive than you might think. I used to have a lot of trouble with KiCAD but then I watched the getting to blinky 5.0 series by contextual electronics and that helped tremendously.
All the best
