How should I put a disclaimer in my thesis indicating that I am not responsible for any misuse of my work?
Talk to your professor.
Your professor is going to be the one marking your paper, so they're the natural one for you to ask. As the comments pointed out, it's unlikely that anyone's going to be reading your thesis besides the professor who's marking it, so asking your professor about the best way to ethically address the potential for your research subject to be misused is probably the best way to go.
Your university would also have some form of ethics committee or institutional review board (IRB) that you could talk to, but at your level, if you were doing something that required the IRB to sign off on it, it's likely that the professor has likely already done so before proposing this as an area of research for your undergraduate thesis.