How to get value from ParameterExpression?

I have a method with the following signature:

void Method(Expression<Func<TSource, IEnumerable<TCollection>>> collectionSelector) {}

I need to get the result value of collectionSelector in order to compare the result with another instance of IEnumerable<TCollection>. I'm trying to achieve my objective as in the code below, but I got stuck while I was asked to provide parameter value:

var collectionSelectorFunc = collectionSelector.Compile();
var collection = collectionSelectorFunc.Invoke(collectionSelector.Parameters[0]./*???*/); 

How to put there the actual value of the parameter?