Headset not working in Ubuntu 16.04 on iMac

Question

I install Ubuntu 16.04 on iMac and headphone jack produces no sound.

I read the answers to the following questions but these solutions does not work on iMac!

• No sound device detected

• Laptop headphone jack produces no sound

• Sound not working HDA-Intel Ubuntu 14.04

How do I enable headphone jack produces on iMac?