How do I make a mob grab an other mob?

Hi!

I'm working on a mod that adds various invertebrates mobs in the game, such as insects, arachnids, ecc... And actually I'm creating a praying mantis. The fact is I would like to make it able to grab it's enemies, just like in real life. I've seen this thing in many other mods, like Alex's Mobs, Ice and Fire, Blue Skies ecc...

Keep in mind that I don't know coding, so please don't send too complex things 😅

Thank you.