You can make the ghost block by Decorated Pot.

Reproduce Steps:
1. Place a Decorated Pot and dig at least 2 square deep holes down in front of it。
2. Sneak and point crosshair to Decorated Pot.
3. Place some block in front of the Decorated Pot. When you place the block, you must cancel sneaking quickly.
4. If you success, the Decorated Pot will play fill sound and the block placed sound will not play.

If you sneak on the block just placed, you can through it and drop.
I will show a video that how to reproduce it.