It is really simple to measure volume with displacement.
All you need is a cylinder that can fit the object, water, and the object itself.
First, you fill in the water, then you calculate the volume of the water.
Next, you add the object and calculate the volume, the difference between the initial and final is the volume of the object.
But if the object is less dense, like wood, then you need to add something that can make the wood stay in place, like an iron block.
First, pour water into the iron block and calculate its volume.
Then you put the wooden piece in and put the iron block above to prevent it from floating and measure the volume.
The difference between the initial and total i the volume of the wooden piece.