According to a report on Discover wildlife, the answer is "yes". An elephant calf sucks its trunk, not out of habit, but does it as a sort of reflex which helps promote its ability to breast feed.
The calf, when it’s not feeding may also suck its truck to help it relax.
Just like human babies, elephant calves have no experience on how to use their appendages, and must be taught how to use them effectively.
They learn to develop their skills by exploring their environment, touching their parents or other herd members.
Their surroundings play heavily into shaping the use of their trunk. There are more than 50 000 muscles within an elephants truck so it takes complex skills to manoeuvre it effectively.
One would think that elephants outgrow the habit of sucking their trunks, but research shows that elephants of all ages do it.
Large bulls have been observed sucking on their trunks when they are nervous or stressed as a possible coping mechanism.
Here is a video of a cute baby elephant charging.