Seattle announced the coaching additions on Monday.
Candaele, 54, spent last season as the Texas Rangers' field coordinator and previously spent four seasons as the minor league infield and base running coordinator. Servais says Candaele will work with outfielders and on base running in Seattle.
Hampton, 43, spent the past two seasons as a pitching coach in the Los Angeles Angels minor league system after concluding a 20-year playing career. Hampton was originally drafted in the sixth round of the 1990 amateur draft by the Mariners.