The iOS Cryptographic Modules, Apple iOS CoreCrypto Module v6.0 and Apple iOS CoreCrypto Kernel Module v6.0, require no setup or configuration to be in "FIPS Mode" for FIPS 140-2 compliance on devices using iOS 9.
For complete instructions about proper use of the modules, refer to the Crypto Officer Role Guide for FIPS 140-2 Compliance: iOS 9 (PDF).