The easiest way is to open the file in Audacity and export as wav. Caf is not a supported file type in Wavelab.
It’s possible to Import/Open Unknown Audio File in Wavelab 9 and Wavelab 8, but you have to know the sample rate, bit depth, etc, and it’s a bit of trial and error, and doesn’t always easily open a caf file correctly, especially in Wavelab 8.
But I wondered, what program or device made the caf file you’re working from? Seems rather unusual to be working with caf files to me.