Well now @
Gbaby86 ......... welcome to posting to ye ol forum .......
A "rock" inside the engine is a new one on us (as far as I recall).
@
steve99 , @
ryoma have a couple of good ideas there (if you can see it).
Since @
fumanchu1 and @
go_a_way1 done used a couple of my back-in-the-day ideas ........

......... I'll have to think on this fer ah spell.
hmmmmm........no good ideas from the old days. Back then. if it were a OHV engine, we would have simple taken off the valve cover and picked the rock out; a flathead, we would have just it lie in the bottom of the oil pan.
IF you can see it, the vac or grabber tool would be my weapon of choice.
IF you can see it and can get a rod to it ...... the redneck way would be to smash it to bits (and not worry about the bits).
If it has fallen to the bottom of the cam chain cover, I'd be tempted to just leave it there. There appears to be enough room down there for it to co-exist with the moving parts.
Sort of like a kidney stone, if it just stays put ..... there is no problem ..... but if it moves, it can cause you great pain.
humfrz