A man has been arrested on suspicion of illegal metal detecting, often known as nighthawking.
Norfolk Police said officers patrolling Methwold Hythe, near Downham Market, spotted activity in a field at about 02:30 BST on Monday.
A man in his 40s was arrested on suspicion of theft.
Officers said a metal detector and spade were seized along with a quantity of metal coins.
The suspect was taken to King’s Lynn Police Investigation Centre for questioning, and was released on bail until 12 June.
