Have you tried any troubleshooting at all to try to resolve the beeping noise? Just some examples:

• Powering it off for 3 minutes to see if that solves the issue?
• See if using a different power socket elsewhere in the Home makes any difference?
• Tried the Sub ‘bonded’ to a different Sonos Room. (If available)?
• Tried a different Power cable (if available)?
• Tried different audio sources?
• Tried it both wired to the LAN, aswell as wireless?
• Factory Resetting the device (as a last resort)?

If not, then perhaps give those a quick try to see if it might just resolve the matter.

Hello I tried but issue did not get resolved ; as soon I plug my sub to power outlet it started making beeping noise.

In that case I suggest that you perhaps contact/chat to Sonos Support Staff via this LINK. Hope you manage to get it sorted.

I’m getting Same issue and need help !!

Then I’d recommend following the suggestion in the post previous to yours!

Certainly, this could be a failure mode of SUB, but also stay alert for unexpected correlations.

I was working with an audio unit in the electronics shop on a military base. During final test I noticed a periodic rude noise emitted by the unit. I was devastated and annoyed. After a few minutes, out of the corner of my eye, I noticed a large rotating radar array outside the building. Each time the array swung in my direction there was a rude noise.