VBA Partial String - Put First 4 Characters Of One Cell Into Another

I haven't had the need to work with partial strings till now and having difficulty finding the right context in other threads. I need to put the first 4 characters of one cell into another cell. The line in the below code with the comment is the one I need. It's the only one where I need only part of what is in the cell.

It should be = the first four characters of cells(zRow, "A")

Code:
Dim LastRow As Long
Dim zRow As Long
Dim cRow as Long

LastRow = Sheets("Datasheet").Range("N65536").End(xlUp).Row
zRow = 1
cRow = 2

[Code] ......