This is not a massive hillfort in the impressive way that Castle Ring (on fairly nearby Cannock Chase) is and I can find no trace of any mounds and ditches, even from the aerial photo available on Multimap.com- photographed at the wrong time of year perhaps?
It is, however, in a pleasant setting and worth a walk if you're in the area. The hill itself is on private land, and divided between more than one landowner. A public footpath passes close by the bottom of the unwooded side of the hill so a fairly close look is possible and for those with a more optimistic view towards the current trespass laws a walk up the hill is also possible; in practice I've never experienced being harrassed by an irate farmer.
I found the following quote in a 19th century description of Leicestershire. The county boundaries have since been moved and Cadborough Hill is currently situated in Derbyshire:
"[Overseal] maintains its poor jointly with Nether Seal ; and between the two villages is a hill called Cadborough, supposed to have been an ancient British station, probably in connexion with that of Seckington, in Warwickshire. On the south side of the hill is a valley, called Dead-Dane Bottom ; and in an adjoining field is a tumulus, where human bones have been turned up by the plough."
Sadly, I can find no trace whatsoever of the tumulous mentioned in the quote.