What is equivalent of combobox's property 'ItemData' of vb6 in c# windows forms of combobox

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C#

SQL-Server

SQL-Server-2008

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hi my name is vishal.
I was wondering what is equivalent of combobox properties of ItemData and List of vb6 in c# windows forms with sql server2008?
I know this is naive question but with this answer i can solve my other problems with combobox in c# windows forms.
Given below is code in vb6 of using ItemData property and List property of combobox into table named:dialyser in Ms access.

Private Sub loadPatientID()
    On Error GoTo errh
    Dim vSQLStr As String
    Dim LPatientID As String
    vSQLStr = "select p.patient_id as patient_id,n.patient_first_name as patient_fname, n.patient_last_name as patient_lname from patient_name n,patient_id p where n.patient_id=p.patient_id and n.status = true and p.patient_id not in (select patient_id from dialyser where deleted_status=false);"
    Dim oRS As New ADODB.Recordset
    If (adoDatabase.State = 0) Then
        adoDatabase.Open
    End If
    oRS.Open vSQLStr, adoDatabase, adOpenForwardOnly, adLockReadOnly
    
    cboPatientID.Clear
    Do While Not oRS.EOF
         '// Do something with the data'
         LPatientID = oRS.Fields("patient_id").Value
         LPatientID = Replace(Space(6 - Len(LPatientID)) & LPatientID, " ", "0")
         cboPatientID.AddItem oRS.Fields("patient_fname").Value & " " & oRS.Fields("patient_lname").Value & "|" & LPatientID
         cboPatientID.ItemData(cboPatientID.NewIndex) = oRS.Fields("patient_id").Value
         oRS.MoveNext
    Loop
    oRS.Close
    Exit Sub
errh:
    MsgBox Err.Description, vbCritical
End Sub
Private Sub Command5_Click()
On Error GoTo errh
Public adoDatabase As New ADODB.Connection
Dim rs As ADODB.Recordset
If (adoDatabase.State = 0) Then
        adoDatabase.Open
rs.Open "dialyser", adoDatabase, adOpenKeyset, adLockOptimistic, adCmdTable
rs.AddNew
    rs("dialyserID").Value = txtDID.Text
    rs("manufacturer").Value = cboManufacturer.Text
    rs("mfr_ref_number").Value = TxtMFRRefNo.Text
    rs("mfr_lot_number").Value = TxtMFRLotNo
    rs("mfr_date").Value = CDate(dtMFRDate.Value)
    rs("exp_date").Value = CDate(dtMFRExpDate.Value)
    rs("start_date").Value = CDate(dtMFRStartDate.Value)
    rs("packed_volume").Value = TxtPVol.Text
    rs("dialyzer_size").Value = cboequipmentType.Text
    rs("patient_id").Value = cboPatientID.ItemData(cboPatientID.ListIndex)
    rs("row_upd_date").Value = CDate(Now)
    rs("user_id").Value = pUserID
    rs.Update
MDIForm1.updateUserActivities rs("agn").Value, 4, txtDID.Text & " - Dialyzer detail was successfully assigned to the patient - (" & cboPatientID.List(cboPatientID.ListIndex) & ")"
    MsgBox "Dialyzer detail was added successfully", vbInformation
    Unload Me
    Exit Sub
errh:
    MsgBox Err.Description, vbCritical
End Sub

where cboPatientID is name of my combobox in vb6 adodb with Ms access.
I just want to know what is equivalent of combobox(cboPatientID) properties ItemData and List of vb6 in c# windows forms.Can anyone help me please?Any help or guidance in solving of this problem would be greatly appreciated.