What endnode said is correct. nRF chips do not have in built EEPROM. That said, they can be simulated and we have an example that does this simulation on RAM. You can find this at
SDK\examples\peripheral\twi_master_with_twis_slave\eeprom_simulator.h file.
This example was designed to simulate EEPROM on Nordic chip for booting the code. That is it assigns configurable part of flash as EEPROM and loads the code from it to RAM and runs it. The interface with simulated EEPROM is TWI and you can later decide to switch from/to simulated EEPROM to external EEPROM without changing the code. The header file is quite simple and see the main.c to see how it works. If you have questions you can ask here.
