This method is also called Expression or Scarification and is used for citrus peels in particular.

The whole fruit is placed in a device that mechanically pierces it to rupture the essential oil sacs, which are located on the underside of the rind. The essential oil and pigments run down into the device’s collection area.
The whole fruit is pressed to squeeze out the juice and the oil.
The oil and juice that are produced still contain solids from the fruits, such as the peel, and must be centrifuged to filter the solids from the liquids.
The oil separates from the juice layer and is siphoned off into another receptacle.