"I would like to know if Dried Fruits are good source of calories when it comes to backpacking"
That depends on how you look at it. They're tasty and have lots of potassium, among other nutrients, but the caloric density may not be especially high. Most are well under 100 calories/ounce, and some are labeled as below 80 calories/ounce. Most of the high caloric density foods will of course contain fat, but even among carbohydrate sources, you can get more calories from some other things. Many people, myself included, like to use relatively high caloric density dried fruits as one of their carbohydrate sources, but to call on some others sources as well, both for variety and for the calories.