...the climb is all there is. You can choose from one of two sets of stairs for this one!
The ones that face Inverness Castle are known as Raining's Stairs. They were named after a John Raining of Norwich, who in 1747 bequeathed £1,200 to a fund for the building of schools in the Highlands. The fund was run by The Society for the Propagation of Christian Knowledge who opened Raining's School at this location. The building was finally demolished in the 1970s.
The adjacent slope that runs along the stairs revealed evidence of earlier settlement during a 1993 dig. Medieval timber buildings, more specifically. You'll catch a good alternative view of the Castle and it's Jacobite area curtain wall from here too. This elevated area is sometimes referred to as Barn Hill, opposite Castle Hill.
On the other hand, you may have chosen Market Brae Steps for your ascent. A handy shortcut between the residental area and the High Street, it's been the site of trade since the 18th century at least. In the past it was your first stop for tobacconists, umbrella makers, drapers and in more recent times, vinyl record collectors!
As for the cache itself, if you're feeling the muggle factor, the hint will help. Enjoy!