First off, you want to have a forged ball, not a cheap one. That ball is the only thing between you and your trailer, or fifth wheel parting company going down the road...
It's 2 metal surfaces sliding against each other under load so it need to have a boundary lubricant applied. Chassis grease, spray grease or any grease for that matter (even KY will work)....lol
If you are wearing the plating off the ball (and plating tells me is't a cheap, not forged ball), that indicates a dry surface and the 'wearing' is not really wearing, but the coupler is seizing to the ball itself (that is what you hear, the noise).
I know, no one likes a greasy ball (gets on your clothes if you rub against it).
Myself, I cover my hitch ball when not in use, with a tennis ball with a split in it to fit over the ball. I use a bright green tennis ball that is readily seen.
A lubricated ball will also improve handling as it will allow the trailer to track truer behind the tow vehicle....