Add the following dependencies to your application.
compile 'com.facebook.stetho:stetho:1.5.0' 
compile 'com.facebook.stetho:stetho-okhttp3:1.5.0' 
In your Application class' onCreate method, call the following.
Stetho.initializeWithDefaults(this);
When creating your Retrofit instance, create a custom OkHttp instance.
OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder();
clientBuilder.addNetworkInterceptor(new StethoInterceptor());
Then set this custom OkHttp instance in the Retrofit instance.
Retrofit retrofit = new Retrofit.Builder()
    // ...
    .client(clientBuilder.build())
    .build();
Now connect your phone to your computer, launch the app, and type chrome://inspect into your Chrome browser. Retrofit network calls should now show up for you to inspect.
 
                