While in object mode, press A to cycle through available items (rings, monitors, enemies, etc.). Place Object (C button):
Furthermore, for fans, it's a chance to experience Sonic 3 & Knuckles in a radical new way, experimenting with levels and characters in ways never before possible. sonic 3c delta debug mode free
"Is there a free way to get this on original Sega hardware (EverDrive)?" Solution: Yes. Patch the ROM as described above, load it onto your EverDrive or MegaSD. The Debug Mode button combo works exactly the same on real hardware. No extra purchase needed. While in object mode, press A to cycle