The repercussions of getting caught would depend on the situation:
- Whether you are making money on the side. If no, then I’m not so sure that would be considered moonlighting
- If you are working in company time and using company resources for your startup
- If you are working with the existing company’s clients
- If you are starting up as a competitor with your existing employer
If it’s 1 and/or 2, then you may be terminated. If it’s 3 and/or 4, the company may file a case against you. If it’s neither of the 4, then you’re safe because you really aren’t doing anything that would damage the company.
Also, make sure not to use your company resources (laptop, internet, etc.) when working on your own thing.