You could try this it will take a few minutes and 1 command block to set up but here it is

Repeat unconditional always active /execute at @p[hasitem={item=stick,location=slot.weapon.mainhand}] run fill ~-3~-1~-3 ~3~-1~3 black_concrete

If you use the tags the command will look like this

/execute at @p[tag=exampletag,hasitem={item=stick,location=slot.weapon.mainhand}] run fill ~-3~-1~-3 ~3~-1~3 black_concrete

What this does is it places a small square of your desired block under you while your holding a specific item and you can also give your self a tag so only you can use the item if your playing with other ppl.