form submitted value as token
Tokens are just a representation of some other data structure that exists.

You can not convert an arbitrary value into a token. What you need to do is store the value and then define a token for that stored value using hook_token_info()/hook_tokens().

I understand it's a per-user value, so the simplest option seems to define a field on the user entity, I don't quite understand why you don't just show that in the profile. Then you can easily access it as a token when using the token module.