As I understand ODP.Net support .NET Framework 4.6.2 and 4.7, Please let me know is there any other way to connect Oracle DB from my existing application which still using .net framework 2.0 ?
Oracle still offers a ODP.Net library for .NET 2, you can download it from their web site (both 32 bit and 64 bit ODAC downloads)
http://www.oracle.com/technetwork/topics/dotnet/downloads/index.html
Edit: it seems like the .Net 2.0 driver is unmanaged and requires oracle client libraries to work. There is a SO question regarding the deployment of Oracle Client via ClickOnce, which explains the process in some detail. You essentially need to compile your application for the platform(s) you want to support and make sure the oracle client libraries are included in the deployment package. The SO question is a bit older and refers to oracle client 11, so some of the libraries the unmanaged driver depends on will have changed.