Try this :
Imports System.Data.OleDb
Public Class homemain
Dim cnn As New OleDbConnection(<connection string="">)
Dim cmd As New OleDbCommand
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)handles Button1.Click
cnn.Open()
cmd.Connection=cnn
cmd.CommandText="select empname from employee"
Dim dr As OleDbDataReader=cmd.ExecuteReader
While dr.Read
cmbempname.items.add(dr.item(0))
End While
dr.close()
End Sub
End Class
Hope, This will help you.