If you want it to just be a page and not a field at all you can use CB Auto Actions for that. Create an auto action in CB Auto Actions > Auto Actions with the following.

Global
Triggers: None
Type: Code
User: Self
Access: Everybody
Code
Method: PHP
Code: YOUR_PHP_HERE
Output
Display: return

Now save your auto action. You should find a URL to directly access it under the Global tab. You can now also create a Joomla menu item to your auto action by setting menu type to Community Builder > Plugin followed by setting Plugin to CB Auto Actions.

If you want it to be a field AND a page you can use CB Content Bot to substitute the field into a Joomla article then create a Joomla menu item to that article. For substitution usage information see the below tutorial. Be sure to use a userfield substitute for this so it outputs formatted displays.

www.joomlapolis.com/documentation/279-community-builder/tutorials/18353-using-substitutions-throughout-cb