ADC sampling rate and signal bandwidth for FHSS
So for frequency hopping spread spectrum (FHSS),when the receiver is unaware of the transmitter's hopping pattern, does that mean the ADC sample rate needs to be higher than twice the entire hopping bandwidth?

Yes.

If I use a 2Msps (4x data BW) ADC it looks like I will still recover my data; sure it under-samples some of MHz modulated frequency but it does capture entirely my data.

No.  See above.  It'll alias whatever is in the entire 24MHz band into the 1MHz that it can resolve, or you'll precede it with an anti-alias filter and lose $\frac{23}{24}$ of your signal.
On the bright side, if you're taking 24MHz worth of bandwidth and only using 1MHz of it, that's close to $14\mathrm{dB}$ of processing gain, so while you need an ADC that's 24 times faster, it can be 4 bits narrower.