Death if angel in hand in Minecraft?

Can I do it somehow that if you have a fishing rod in minecraft in your hand that you will be killed?

With a plugin something like that is safe, otherwise there's probably still the possibility to do it with command blocks.

You have to write in a repeat command block:

/ kill @a [nbt = {SelectedItem: {id: "minecraft: fishing_rod"}}]

Should work 100%