Hi Sumeet,
Please refer below sample.
Vb class can access in C# code behind, refer below sample.
Default.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
Customer cust = new Customer();
Response.Write("Name is: " + cust.GetFirstName() + " " + cust.GetLastName());
}
Customer.VB
Public Function GetFirstName() As String
Return "Mudassar"
End Function
Public Function GetLastName() As String
Return "Khan"
End Function
Output
Name is: Mudassar Khan