I found 2 versions of this, don't know if it is the right song or not. If there is more, I didn't find it:

Version 1
Zacchaeus was a wee little man,
A wee little man was he,
He climbed up in a sycamore tree,
For the Lord he wanted to see;
And as the Saviour passed that way,
He looked up in the tree
And He said: "Zacchaeus, you come down,
For I'm going to your house today,
For I'm going to your house today.


Version 2
Zaccheus was a very little man
And a very little man was he.
He climbed up into a sycamore tree,
For the Savior he wanted to see.
And when the Savior passed that way,
He looked into the tree and said
"Now, Zaccheus, you come down,
For I'm coming to your house for tea"