macros - Find and replace in Excel

I have a table in sheet 1 has two columns A and B. I created a macro to find the value of A1 in sheet 2 and replace the value of B1 instead of value A1 in sheet 2

I am looking to improve the macro to cover the whole range of A and B columns.

    Sub Find_Replace()
'
'
    Sheets("Sheet1").Select
    Range("A1").Select
    Selection.Copy
    Sheets("Sheet1").Select
    Range("B1").Select
    Application.CutCopyMode = False
    Selection.Copy
    Sheets("Sheet2").Select
    Selection.Replace What:="Value 1 ", Replacement:="value X", LookAt:= _
        xlPart, SearchOrder:=xlByColumns, MatchCase:=False, SearchFormat:=False, _
        ReplaceFormat:=False
End Sub

sample table

** looking to improve Range("A1").Select to cover all available cells in range A and B