... Is there a simple way to accomplish this?
The short answer is no due to Apple's obsessive desire to keep each individual users' data separate and secure from one another, regardless of any personal relationship. I understand what you want to do though, so the longer answer is yes, with caveats.
Refer to What to do before you sell, give away, or trade in your Mac - Apple Support. Perform Steps 3, 4 (if applicable, depending on its macOS version), 5, and 6.
Do not omit any of those steps for reasons that will become apparent later. Pay particular attention to the implications of iCloud in Step 5, since anything stored in iCloud will remain under the control of your husband's Apple ID and cannot be transferred to any other Apple ID under any circumstances. Likewise, purchased content (movies, music etc) will remain under your husband's Apple ID, and cannot be played on that Mac without his Apple ID credentials.
Also, turn off Find My Mac as described in Add your Mac to Find My - Apple Support. You should also review the following paragraph:
"When you turn on Find My Mac, the ability to locate, lock, or erase it is turned on automatically. Depending on the model of your Mac, Activation Lock is also turned on automatically to prevent anyone else from activating and using your Mac, even if it’s completely erased. See Activation Lock and Find My."
Then, methodically read and apply the following: Change the name of your macOS user account and home folder. Pay particular attention to the boxed note at the beginning. This is where your Time Machine backup becomes critical, because it really means what it says: if things don't go as planned, both you and your husband may be locked out of that Mac. The Time Machine backup is your only safety net.
After the conclusion of its Step 8, sign in to your newly renamed User Account, and "sign in" to iCloud using your own Apple ID credentials. Same for FaceTime and Messages.
Don't forget to turn on Find My Mac assuming that's what you want.
That should effectively accomplish what you seek.
It may also be a good time to consider How to add a Legacy Contact for your Apple ID - Apple Support.