I understand, but how do you prove it? Can the ideas learned or developed not be coded again? And if code was actually stolen, can it not be modified enough, in style if not in essential content, to distinguish it from the original code? At least enough for plausible deniability? Again, I'm out of my depth here, especially since I nether code nor trade options.
NDAs on code are useless, a developer can take any code and modify it enough to look like they have developed it.
If you are the original creator of the program and use interpreted languages like Python, Javascript or Typescript, everything will be in plain text, so you can't do much about it. Everything could be copied easily.
If you use a proper language like c++ or c# at least your code will be compiled and packaged into a dll. There you can obfuscate your code with specific tools for it. Still there are tools to reverse engineer the code but it will be much more complicated than if the program output was in plain text.
Either way, every time we are asked to sign an NDA about the code base we laugh at it. Whoever asks for an NDA to a developer has no clue about developing software.