Wireshark on proxy
 

Is there any way to access the traffic on wireshark on a proxy running ubuntu system ..... the proxy is set in the browser ......

wireshark is a packet sniffer, it doesn't care how you configure your browser in the slightest. It will capture all traffic that you tell it to, on the box that it's running on. I'm not sure what your angle is in terms of the proxy, but if you use a default setup against the right interface then it will capture that traffic, yes.