Hi JeongHan Chang,
We would need to check some items to understand why this happens and perform a series of troubleshooting to resolve it. First, unplug any devices that are connected to the Surface, including the Type Cover.Inspect the PSU for any physical damage. If the PSU looks good, reconnect it and see if the noise will be present when the Surface is charging with no peripheral devices connected to it. If there are no changes, try a different wall outlet.
Next, make sure that no apps are running. To see if an app remains running in the background, use the Task Manager. Long press on the Start button and choose Task Manager. You can also click on the CPU column to sort the apps according to the highest usage. If an app that you don't use has high CPU usage, select it and click on End task at the bottom of the Task Manager window. See if the noise will disappear when the app has been closed.
Let's also check if the noise will be present in the UEFI. Disconnect the PSU and switch off your Surface. Once the device is completely off, press and hold the Vol + then press and release the power button. Reconnect the PSU and confirm that the tip is lit. Observe if there will be an unusual sound or noise. If the problem occurs in the UEFI, then what we're dealing is a hardware issue. Please contact Microsoft Support or take the Surface to a Microsoft Store for assistance regarding such issues.
If the problem does not reside in the UEFI, we would have to continue troubleshooting the software. Please reply to this post with your findings. I will be notified when you do and I'll get back to you the soonest I can so we can work towards a resolution together.
Regards.