I have a pair of fencing pliers like to pair shown but in Jim's circumstance they aren't that helpful.
Trying to pry a staple or nail horizontally from a round post is a PITA and usually does more damage than necessary to the wooden post.
While I use a small spud bar for situations like this, Jim's method is sound and probably does less damage
Example
https://www.grainger.com/product/38G...w63h3:20501231