How do you become a customs officer in an airport?

To become a Customs Officer you will have to take the Civil Services Examination which provides entry into 27 different services including the Indian Customs & Central Excise Services. Customs Department is one of the two main tax collecting departments of the government whose function is divided into two broad areas:

The control of imported and exported goods for the purpose of duty, statistics and checks for entry of prohibited and restricted goods, especially smuggled drugs.