Can I hook up a 4ohm sub and a 2ohm sub together to a 1 ohm amplifier?

More info is required on the sub. We have NO idea if the sub is DVC or SVC.

It can be hooked up to any type of impedance and in parallel or in series.

But the problem is...if it's NOT wired to that impedance on the amplifier or if it's wired to a 1 ohm load to an unstable 1 ohm amplifier, then the amplifier will run extremely HOT and go into the protect mode until it cools down. This becomes dangerous for the amplifier and the vehicle. It will have a chance to melt and catch on fire.

Switch to a single sub. Go with neither the 4 ohm or the 2 ohm. If you want 2 subs, then replace the 4 ohm for another 4 ohm or replace the 2 ohm for another 2 ohm.

Use OHMs law. rT= r1+r2...rN for series and for parallel, rT= the inverse of the sum of the inverse of all the speakers. That way you know if your impedance total is not less than the stability of the amp.  You should see the total is just a little more than 1 ohm, which is fine. But, consider the other specs of each speaker, such as free air resonance, cone area,  RMS power rating and frequency response curve. It will be a nice exercise for you, building this to see how your carpentry skill adds up.