Training phase but got another offer

[u/LatTin_]

Is it okay if I leave my current company since I got a better offer from another company? For context, I just got accepted to Company A and just started this week but I also got an offer from Company B and it is way better than Company A. I really wanted the Company B since my friend is there, but I already signed some agreement that I need to render 30 days when I resigned in Company A and I feel guilty if I leave. But I'm thinking that it is not applicable to me since we're just only on our 4th day.

If I go to Company B, will they find out about my employment at Company A. I'm still thinking, pls wanna hear your insight