How can I make the ID of any custom field searchable in the global search? For example, if I want to view a custom field, I have to find it in Customization > Lists, Records, & Fields > etc. But if I know the ID of the field because it's on the form I'm looking at, I want to be able to just search that ID and have it show up in the search results. How can I do this?

What do you want to navigate to when you search it? Like the settings/configuration of the custom field?

@Dan Warner If you use Strongpoint it will show up as a Customization in the global search. I believe they still have a free version you can use. Highly recommended. Alternatively, consider using the Google Chrome Extension NetSuite Advanced Field Help. In has link to the custom field hyperlink as well as some other valuable tools that appear when you click on the field help for each object. Hope that helps.