Yeah you can but it depending on how it set up so like if you have only single NM cable then it will be no issue but if you have two cables it can affect the set up.
Make sure that you understand the switch loop is differnt so before you start take apart look at your switch to see how it conferated first that useally can save yourself alot of headache.
Second thing be aware the junction box in the fan / light combo unit there is not a really much room at all so you may have to make a junction box next to it ( if you have attic that is not a issue but have no attic in this area let me know I know there is other way you can do.)
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