cmds.ls( cmds.listHistory(transformOrShapeName), et='cacheFile')
fill in transformOrShapeName, or just skip it alltogether if your using the base selection list. So for example to make a dictionary of all selected objects with cache you could do:
dict([(item, cmds.ls(cmds.listHistory(item), et='cacheFile')[0]) for item in cmds.ls(selection=1) if len(cmds.ls(cmds.listHistory(item), et='cacheFile')) ] )