Yeah here's one way of doing it:
1) Create a bomb prefab with Item component. Change item type to weapon. In Usage settings, add a 'On use' action that spawns the next prefab we create.
2) Create another bomb prefab with a Logic component. Make the event a timer (for how long you want it to explode). For the action make it spawn the last prefab we create and kill itself.
3) Create a third prefab for the explosion. Give this a Trigger component, and on the 'On enter' action, make it do whatever you want (kill player, change their health, etc). And then add a Logic component with a timer action, and make it kill itself after a certain amount of time.

As for how to "spawn them holding the bomb", I'm not sure. Easy way I know of is just placing the first bomb prefab right in front of the player.