包函数内的重定向/截取函数调用

Suppose I'm calling function PackageFuncA which exists within a 3rd party package (i.e. a library from CRAN). PackageFuncA in turn calls PackageFuncB within the same 3rd party package. Is there a way to call PackageFuncA such that when it calls PackageFuncB, it will in fact call my own implimentation of PackageFuncB? In other words, can I intercept the call to PackageFuncB?Suppose I'm calling function PackageFuncA which