Create custom field in user settings page

I wish to add an extra field (secondary email id) in user settings page. It should be editable. Is there any custom hook available or any other option…?

Did you find a solution to add custom fields to the user’s profile?
I have the same need with totally different fields from the classic information. I’m also wondering if it wouldn’t be possible to create an extra tab with all the data I want to add to the user. Have you experienced this way?

Does anyone have a solution?
Thank you.