CRJ-900 First Officer reported a dual IRS failure in flight. The flight crew requested vectors and performed an air turn back. The flight crew performed a no gyro approach and landing at departure airport.

Narrative

We were operating Aircraft X; ZZZ-ZZZ1 on Date. On the climb out (900 ft. AGL) the PM (Pilot Monitoring) IRS system completely failed. The PF (Pilot Flying) (mine) IRS continued to operate for a bit but also eventually failed and disconnected the Auto Pilot. We alerted departure to the loss of instrumentation and requested a vector. Using the magnetic compass and standby ISI we leveled off at 5;000 ft. and flew the vector. Shortly after we requested a climb to 10;000 ft. to leave the IMC conditions and to better run our QRH/Checklist. We soon realized the failure and decided that a return to ZZZ was the best option. The clouds were high enough for an eventual visual approach. ATC gave us a no gyro approach until we were able to get the ILS GS and then runway insight to land. Upon landing there was no further action required beyond returning to a gate and alerting Maintenance. We are unsure of the cause for the failure. The only reason we had to return is both systems fully failed.There is not much we can do about the failure. I do think having flown a no gyro approach in the sim I felt much more comfortable with the situation as a whole.