Hi and welcome to the GMC!
Don't worry, you're posting this question at the right location.
Try the following approach:
Have a variable in the character object that represents which item the player is currently holding and set it to the value noone when the character isn't holding any items.
Then have some code in the character's step or begin step event that teleports the item to the character.
For example, you could create a parent object obj_carriable_item_parent that is the parent of every item object that the character can carry.
Then in the create event of the character object, you initialize the variable carrying_item to noone:
In the keyboard pressed event of the character object for the key you use to pick up or drop an item, you update the variable:
GML:
if carrying_item == noone {
carrying_item = other.id;
} else {
carrying_item = noone;
}
Finally, in the step event of the character object, you teleport the item to the character:
Code:
if carrying_item != noone {
carrying_item.x = x;
carrying_item.y = y;
}
Let us know how that goes and if you have any questions, feel free to ask them.