How to attach an object to the rig?

Hi guys. I have a little problem with animation. For example in maya, when you animate, you can attach an object to the arm “Baseball” and animate the arm and it will follow the arm controller but in blender, i couldn’t do it. When i do the animation, like picking objects, it is really hard to make it without flickering.

Use a copy location or child of constraint on the ball to the desired bone.

is it possible to do the same with ik/fk controller?

yep…you can use constraints on any 2 objects as long they have transform channels.
object to to bone,or object to ik target object etc etc…