If it feels like something is blocking the slot, then that's probably it.
MacBooks very commonly will reset the CD drive as you power on. That is NOT the same as eject.
Try a couple of different methods for forcing the drive to eject the disk that may be stuck.
Here's a long-time trick that may help eject a stuck disk on a Mac. (same trick worked back when Macs still had floppies
)
Shut your MacBook off.
Press and release the power button to start up again.
Immediately (before the boot chime completes) press and hold the trackpad (or mouse) button. If there is something ejectable (in the right position, and not completely stuck), then shortly after the screen lights up, the eject should work. Watch the disk slot as it tries to eject, as it might be pushing something out, but failing. You might even see a brief appearance through the slot, and then it gets sucked back in. Sometimes you can grab the edge as it appears, and gently tug it on out.
Another possibility is that a CD or DVD is in the drive, but not in the right position. Sometimes you can get it to eject properly, by using a second CD disk to push firmly into the slot, which might get a disk back in the ejectable point. (sometimes works, sometimes not - but worth a try.)
And, finally, Macbook optical drives are not known for great reliability, so it's also possible that the drive has simply failed, or the eject motor is not working properly. Both have the same result, and the same fix (replace the drive, or use an external)