How to add the user id to any record in a data entry screen

Hi
For each record for my table “Garantias” that I insert, I want to choose an user (WordPress User). The thing is that users are my customers as well and I want to enter their services and their warranty expiration date.
I have added the field Id; however, I don’t know how to add a combobox field where I can choose the username from there. You know what I mean?

That would be so useful for me.

I would appreciate your help with this issue.

Thanks in advance.

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