West Virginia. I work for a small business and I do work on the side. I get paid salary. I am not under any type of contract. I have customers contact me through word of mouth and in no way concerning or dealing with the company I work for. However I did use company equipment which I had permission to use in personal time. The work and supplies for the jobs I do on the side are all paid for by me. Is it embezzlement if I keep the money being paid to me? Instead of giving it to the company even though it had no affiliation to the company other than using company equipment?
You didn't give any real details of what you do but I will give you an example using my own industry.
I am a tax professional. I work for a firm. It is not uncommon for tax professionals who work for a firm to have some private clients. If I buy my own software and take care of my private clients from my home, using my own software then its not a problem because I do not have a contract that prohibits that.
However if I take care of my private clients using software that my employer installed on my laptop, or worked with the private clients off the clock/after hours at the office, then that would be considered a form of embezzlement...and if not embezzlement, would certainly get me fired.
So, the devil is in the details, and you have given no details.