Amazon has usb scsi adapters, I dont use apple devices, but i'd guess that would work. https://duckduckgo.com/?q=usb+scsi+adapter&ia=web
Hmm, what I see on Amazon is a lot of USB-to-SATA adapters, not SCSI. eBay has used, old USB-to-SCSI adapters, which is one of the options that's sometimes recommended.
Looking at "scsi to usb" on amazon.com, most of the options I see are SATA, IDE or even parallel printer port adapters, but nothing which allows a SCSI device to be connected to a USB port.