In below example I’m retrieving “Account” object “Industry” picklist values and populating on lightning component using ui:inputSelect.

Apex Class:

public class AccountAuraController {
    @AuraEnabled
    public static List<String> getIndustry(){
        List<String> options = new List<String>();
        Schema.DescribeFieldResult fieldResult = Account.Industry.getDescribe();
        List<Schema.PicklistEntry> pList = fieldResult.getPicklistValues();
        for (Schema.PicklistEntry p: pList) {
            options.add(p.getLabel());
        }
        return options;
    }
}

Component:

<!--TestComponent-->
<aura:component controller="AccountAuraController" access="global" implements="force:appHostable">
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>    
    <div class="slds-form-element">
        <label class="slds-form-element__label" for="select-01">Select Industry</label>
        <div class="slds-select_container">
            <ui:inputSelect label="Industry" class="dynamic" aura:id="InputAccountIndustry" change="{!c.onPicklistChange}"/> 
        </div>
    </div>
</aura:component>

Component Controller:

({
    doInit: function(component, event, helper) {
        var action = component.get("c.getIndustry");
        var inputIndustry = component.find("InputAccountIndustry");
        var opts=[];
        action.setCallback(this, function(a) {
            opts.push({
                class: "optionClass",
                label: "--- None ---",
                value: ""
            });
            for(var i=0;i< a.getReturnValue().length;i++){
                opts.push({"class": "optionClass", label: a.getReturnValue()[i], value: a.getReturnValue()[i]});
            }
            inputIndustry.set("v.options", opts);
            
        });
        $A.enqueueAction(action); 
    },
    onPicklistChange: function(component, event, helper) {
        //get the value of select option
        var selectedIndustry = component.find("InputAccountIndustry");
        alert(selectedIndustry.get("v.value"));
    },
})

Lightning App:

<!--TestApp-->
<aura:application extends="ltng:outApp" access="global">
    <c:TestComponent />
</aura:application>

Output: