Custom fields can be made visible in “Backlog” as Column. You can add custom fields associated with User Story in “Backlog”. In “Backlog”, you can add new columns using “Column” button in Filter bar. “Columns” drop-down shows all available fields including custom fields. Values are comma separated if your selected custom field has multiple values.

Although, it is possible to add the new status on some boards. For details, see what is status set? And How to create a Status Set?