Text Input Component value option as PHP code

I searched a lot in this forum, but not found an example in using the custom code component in a form with a text input component, where I would like that “value” option was filled with an PHP (or other language) ECHO.
I tried to insert the “custom code” component in value option without success.
I tried to convert to HTML, without success too.
Is there somewhere an simple example, step by step, in this forum or on an Youtube video?
Thanks in advance.
Best regards.