I presume you're wanting this capsaicin to stop them from digging in the garden?
Our dog has a problem with digging - we've found two ways to stop that. 1. Soak the ground until it's really soft - makes a lot of mess all over the dog/cat when they dig, and they don't like it. Easy solution, but uses a bit of water. The second option is to sprinkle wasabi powder or really hot chilli powder on some damp ground where they like to dig - it sticks to their feet and burns their mouth a little when they wash themselves - eventually they'll figure it out (habanero powder would be awesome for this if you can find it).