If you chose to move your base while you have FOBs deployed you will get the option to scrap and redeploy your FOBs at the "Discounted Rate". What this means is that you will get 50% of your deploy cost for them back (up from the normal 10% when just scrapping manually) and you will also be able to redeploy them at that same 50% rate after moving your base, making the move for your FOBs basically "free".
Note that this is only possible by choosing to move your base while you have your FOBs deployed to get the "FOB Scrap" pop up (see screenshot below); simply scrapping your FOBs and then choosing to move will only refund 10% of their deploy cost, and you'll need to pay the full cost to redeploy them at your new location. Please also note that the ability to redeploy at the discounted 50% rate only lasts for as long as you are in movement cooldown; once you cooldown expires they will go back to full cost to deploy them, so make sure you do so as soon as your base is done moving.
Finally, make sure you keep in mind that scrapping FOBs under any circumstances will not overfill your resource storage; if you are already at capacity you may want to make some room for you FOB refund, otherwise it will be lost.