Hello! First you are going to need 4 things:

1. Bow
2. Repeating Command Block (type /give @s repeating_command_block
3. Redstone Comparator
4. Redstone Repeater

First by placing a command block, then 4 blocks away place another one. Get the comparators and repeaters and make this setup:

Now in the first command block, type this:

/testfor @e [type=arrow,r=100]

Now, on your Minecraft, press on the green arrow.

Then type this:

Finally, on the last command block, do this:

Now shoot the bow, make sure it’s far from the machine, or it’ll destroy it. Don’t do it too far, or the command block won’t work.

ALL COMMANDS:

1. /testfor @e [type=arrow,r=100]
2. /execute @e [type=arrow,r=100] ~~~ summon tnt ~~~
3. kill @e [type=arrow,r=100]