What would happen if I took my SIM card out of my Note 5, and put it in my Iphone 6?

Would it give me service? Both phones are locked to the same provider.

Nothing would happen to either phone.
Yes you'd get service if they're locked to the same provider or are unlocked phones. Yes. As long as both phones use the same size SIM card. IPhone 6 uses nano. Finding out what size sim your note uses.

Yes. As long as both phones use the same size SIM card. IPhone 6 uses nano. Finding out what size sim your note uses.