Lightning Component:

<!--SampleComponent.cmp--> 
<aura:component implements="flexipage:availableForAllPageTypes,force:appHostable" access="global">
    <!--Declare Attributes-->
    <aura:attribute name="accountId" type="String" />
    <!--Declare Handlers-->
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
</aura:component>

Lightning JS Controller:

({
    doInit : function(component, event, helper) {
        var accountId = component.get("v.accountId");
        alert('Account Id-' + accountId);
    }
})

Lightning App:

<!--SampleApp.app--> 
<aura:application extends="ltng:outApp" access="global">
    <!--Lightning component-->
    <aura:dependency resource="c:SampleComponent"/>
</aura:application>

Visualforce Page:

<apex:page sidebar="false" showHeader="false">
    <apex:includeLightning />
    <!--Lightning Container-->
    <div style="width:100%;height:100px;" id="LightningContainer"/>
    
    <script type="text/javascript">
    //get account Id from URL
    var accountId = "{!$CurrentPage.parameters.id}";
    
    //Create Lightning Component
    $Lightning.use("c:SampleApp", function() {
        $Lightning.createComponent("c:SampleComponent", 
                                   { "accountId" : accountId }, //Pass Parameter
                                   "LightningContainer", function(component) {
                                       console.log('Component created');
                                   });
    });
    </script>
</apex:page>

URL : https://yourorgurl/apex/SampleVFPage?id=0010I00001dPxYL